Call me skeptical. Squirrels have two litters a year. Right now you are probably between the first and second. The number of young depends on the amount of food available but can go up to 8 per litter, so twice a year you can add 400% to the population.
http://www.crittercontrol.com/servic...ife-cycle.html
I tried marking my territory a number of years ago. I didn't notice any effect but YMMV. That may only work on animals that are afraid of humans.